Encore: Make @babel/preset-env use polyfills by default

symfony/webpack-encore-bundle/1.0/package.json

@@ -1,6 +1,7 @@
 {
     "devDependencies": {
-        "@symfony/webpack-encore": "^0.22.0",
+        "@symfony/webpack-encore": "^0.26.0",
+        "core-js": "^3.0.0",
         "webpack-notifier": "^1.6.0"
     },
     "license": "UNLICENSED",

symfony/webpack-encore-bundle/1.0/webpack.config.js

@@ -41,6 +41,12 @@ Encore
     // enables hashed filenames (e.g. app.abc123.css)
     .enableVersioning(Encore.isProduction())
 
+    // enables @babel/preset-env polyfills
+    .configureBabel(() => {}, {
+        useBuiltIns: 'usage',
+        corejs: 3
+    })
+
     // enables Sass/SCSS support
     //.enableSassLoader()